Many volatile organic compounds are toxic or carcinogenic and it is highly desirable that they should be detected readily so that remedial action can be taken, such as changing filters designed to remove such compounds from breathing apparatus or effluent ducts from process plant, or changing the operating parameters of processes which involve the volatile organic compounds or produce them as by-products.
Traditional methods of detecting volatile organic compounds in gaseous media are based on infrared absorption spectroscopy or gas chromatography. Such methods tend to be slow and require cumbersome equipment. Whereas this may be acceptable in the context of process control in a fixed chemical plant, it may not be so for use in the field.
In U.S. Pat. No. 3,843,257 there is disclosed an apparatus and method for detecting materials in gaseous media in which a gaseous medium is irradiated with microwave energy and optical emissions from the excited gaseous medium are analysed to detect the presence of the materials in the gaseous medium.
However, the apparatus and method described includes a preliminary stage in which a particulate or liquid component of a first gaseous medium is atomised and mixed with a carrier gas prior to being subjected to irradiation with microwaves such as to produce an electrical discharge in the carrier gas which causes the emission of optical radiation from the atomised components of the first gaseous medium.
The apparatus therefore is relatively complicated and more suited to laboratory rather than field use.